Date of Award

1982

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Abstract

Ion exclusion is a chromatographic separation of ionic from non-ionic material on a bed of ion exchange resins. This process has been proposed for the recovery of sucrose from molasses. However, separation of sucrose from the non-sugar and reducing sugar fractions is difficult. On the contrary, separation of reducing sugars from non-sugars is relatively easy. Inverting the sucrose to reducing sugars for further separation by ion exclusion gives a way to recover essentially all the sugars from molasses. Also, it eliminates the need for crystallization, since the reducing sugars can be sold in solution. The total sugar content in blackstrap molasses is, potentially, of great economic value, as much as, say $1.5 million/year for a 5000 TCD Louisiana factory. The ion exclusion process requires a feed material with both suspended and total hardness (Ca('++), Mg('++)) reduced to the lowest possible levels. In this research, pretreatment of molasses, and separation of sugars from non-sugars by ion exclusion were both studied. Molasses pretreatment was accomplished in a novel way using phosphoric acid, sodium hydroxide, and "dilution" water. The pretreatment consisted of dilution, heating, adding acid to 2.5 pH to invert the sucrose and reduce the hardness content, neutralizing, adding more dilution water, and settling. In this work, phosphoric acid gave greater reduction in total hardness than the other mineral acids studied. Also, the final dilution step notably increased the rate of mud settling. The main objective of the ion exclusion work was to establish the main variables and the magnitude of their effects. Six operating variables were studied using a two factorial experimental design. From statistical data analysis, the variables having the strongest influence were the feed volume to the column per cycle as percent of the total bed volume, and the percent of resin cross-linkage. The results were consistent with mathematical models previously proposed in the literature. Ion exclusion treatment produced a clear, lightly-colored invert sugar solution of 98% or greater purity at about 90% recovery. The data obtained were adequate to permit preliminary plant design and cost estimates to be made.

Pages

313

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